The remote sensing market originated with early satellites and goals of global monitoring of terrestrial activities. However, the cost of data and the response times for obtaining data has limited the broad applicability of imagery for use in day-to-day business operations. Nevertheless, for relatively small scale users, such as farmers, city planners, utilities managers and forest managers, the computerized geographic information system is recognized as the information integration tool of the future. Geographic information systems include computer tools for locating geographic coordinates of points within images, for overlaying maps and images, and for making quantitative measurements, such as areas, distances and precise locations of objects, from the images. Applications as diverse as (1) a farmer selecting chemical application strategies based upon expected crop yield predictions, (2) a tax assessor directing a manual inspection of an observed dwelling addition, or (3) assessing timber yields and timber harvest costs from multiple property tracts are but a few of the numerous potential applications of imagery and geographic information systems.
The profit structure of the agricultural industry is heavily dominated by the use of chemicals (fertilizers, pesticides and herbicides), with a trend toward the use of more chemicals. However, since the EPA and world environmental organizations recognize long term hazards of unabated chemical treatments, chemical regulations are throttling the agricultural business. Of equal significance as populations increase, more land is cleared for farming, and reduced food yields per acre lead to higher deforestation and even greater threats to the environment. The recognized answer to these global scale problems is metered usage of chemicals, such that the chemicals are used where they are of maximum benefit. Metered chemical distribution systems are in wide use. However, the data to define the spatial metering values are lacking. Multispectral imagery with submeter resolution and spatial registration is required. The imagery must be available at low cost and with short response times to requests for imagery.
A satellite system known as the SPOT satellite, sponsored by the government of France, is representative of current operational satellite capabilities. This system provides 10 meter resolution panchromatic imagery or 20 meter resolution imagery in the visible/near infrared bands. Geodetic registration is accurate to 15 meters in the U.S. where ground control points are plentiful and well surveyed. Experience has shown that the response time for imagery requests is usually no better than 10 days. The drawbacks to satellite imagery include the potential for cloud coverage (2/3 of the earth is cloud covered), high costs and the inflexibility of satellite imagery collection systems. Custom tailored resolutions, spectral bands and responsiveness cannot be provided by satellite systems.
Airborne imagery is commonly used by many small scale users. Benefits of airborne imagery collection include tailorable resolution, response time and data processing methodology. Drawbacks include higher costs and the need to contract for a dedicated aircraft, flight crew and post-mission processing system.
A variety of airborne sensing and survey systems have been disclosed in the prior art. A survey system for obtaining geophysical data with aircraft using real time differential operation of the global positioning system is disclosed in U.S. Pat. No. 4,814,711 issued Mar. 21,1989 to Olsen et al. An airborne system using two color video cameras and an IR imager head mounted below the fuselage of an aircraft is disclosed in U.S. Pat. No. 5,166,789 issued Nov. 24,1992 to Myrick. Latitude and longitude information obtained from the global positioning system is recorded on each image frame. A system including a CCD camera and a global positioning system receiver for recording an image signal and position information on magnetic tape is disclosed in U.S. Pat. No. 5,267,042 issued Nov. 30, 1993 to Tsuchiya et al. A technique for airborne imaging wherein multiple overlapping images are superimposed by observing a stationary object that appears in adjacent images is disclosed in U.S. Pat. No. 5,247,356 issued Sep. 21,1993 to Ciampa. A technique for generating high resolution images from a CCD camera in an aircraft is disclosed in U.S. Pat. No. 5,251,037 issued Oct. 5, 1993 to Busenberg. A technique for generating high resolution vidicon aerial images is disclosed in U.S. Pat. No. 5,270,756 issued Dec. 14,1993 to Busenberg. An airborne contour mapping system is disclosed in U.S. Pat. No. 3,191,170 issued Jun. 22, 1965 to Lustig et al. A technique for remote sensing using inertial navigation systems and the global positioning system for referencing of remotely sensed data is described by K. P. Schwarz et al. in Photogrammetric Engineering & Remote Sensing, Vol. 59, No. 11, Nov. 1993, pp. 1667-1674.
The examples above are characterized by components integrated tightly to the aircraft so that a dedicated aircraft is required. None of the prior art airborne imaging systems have been practical from the viewpoint of small scale users with respect to cost, resolution, flexibility and response time.